From b5e58e731a06778138a3b9f5a7f98960e9009b88 Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Sun, 28 Apr 2024 23:01:15 +0300
Subject: [PATCH] More drawing

---
 src/bin/flat.rs | 43 ++++++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/src/bin/flat.rs b/src/bin/flat.rs
index d42ded8..23f4965 100644
--- a/src/bin/flat.rs
+++ b/src/bin/flat.rs
@@ -5,7 +5,7 @@ use num_traits::identities::Zero;
 
 pub fn main() {
 	let space = Coil {
-		coil_scale: 2.0,
+		coil_scale: 3.0,
 		coil_r: 300.0,
 		coil_w: 50.0,
 		coil_m: 10.0,
@@ -24,26 +24,32 @@ pub fn main() {
 			gc.fill_color(Color::Rgba(0.8, 0.8, 0.8, 1.0));
 			gc.fill();
 
-			gc.line_width(1.0);
+			gc.line_width(0.5);
 			gc.stroke_color(Color::Rgba(1.0, 0.5, 0.0, 1.0));
 			for y in itertools_num::linspace(-1.0, 1.0, 101) {
-				let base = vec2(-500.0, 0.0);
-				let dir = vec2(1.0, y);
-				let path = trace_iter(&space, base, dir, 1.0);
-				gc.new_path();
-				gc.move_to(base.x, base.y);
-				for pt in path.take(10000) {
-					gc.line_to(pt.x, pt.y);
-					if any(greaterThan(abs(pt), Vec2::from_s(1000.0))) {
-						break
-					}
-				}
-				gc.stroke();
+				draw_ray(gc, &space, vec2(-500.0, 0.0), vec2(1.0, y));
+			}
+			gc.stroke_color(Color::Rgba(0.0, 0.5, 1.0, 1.0));
+			for y in itertools_num::linspace(-1.0, 1.0, 101) {
+				draw_ray(gc, &space, vec2(0.0, space.coil_r), vec2(1.0, y));
 			}
 		});
 	});
 }
 
+fn draw_ray(gc: &mut Vec<Draw>, space: &impl Metric, base: Vec2, dir: Vec2) {
+	let dir = space.globalize(base, dir);
+	gc.new_path();
+	gc.move_to(base.x, base.y);
+	for pt in trace_iter(space, base, dir, 1.0).take(10000) {
+		gc.line_to(pt.x, pt.y);
+		if any(greaterThan(abs(pt), Vec2::from_s(1000.0))) {
+			break
+		}
+	}
+	gc.stroke();
+}
+
 struct Coil {
 	coil_m: f32,
 	coil_scale: f32,
@@ -88,6 +94,13 @@ trait Metric {
 		part_deriv(|p| self.metric(p), pos, 1.0e-3)
 	}
 
+	fn length(&self, at: Vec2, v: Vec2) -> f32 {
+		sqrt(dot(v, self.metric(at) * v))
+	}
+
+	fn normalize(&self, at: Vec2, v: Vec2) -> Vec2 {
+		v / self.length(at, v)
+	}
 	fn globalize(&self, at: Vec2, v: Vec2) -> Vec2 {
 		let h = self.halfmetric(at);
 		transpose(&h.ortho) * diagonal( Vec2::from_s(1.0) / h.diag) * h.ortho * v
@@ -130,7 +143,7 @@ fn trace_iter<M: Metric>(space: &M, base: Vec2, dir: Vec2, dt: f32) -> TraceIter
 	TraceIter{
 		space: space,
 		p: base,
-		v: normalize(dir),
+		v: space.normalize(base, dir),
 		dt: dt,
 	}
 }